第4题

来源：互联网发布：如何用图片在淘宝搜索编辑：程序博客网时间：2024/05/22 05:21
#include <iostream>using namespace std;class Shape{public: virtual double area() const =0;            };class Circle:public Shape{public:Circle(double r):radius(r){}                                       virtual double area() const {return 3.14159*radius*radius;};   protected:  double radius;                                               };class Rectangle:public Shape{public: Rectangle(double w,double h):width(w),height(h){}               virtual double area() const {return width*height;}              protected:  double width,height;                                           };class Triangle:public Shape{public:  Triangle(double w,double h):width(w),height(h){}                  virtual double area() const {return 0.5*width*height;}           protected:  double width,height;                                            };void printArea(const Shape &s){cout<<s.area()<<endl;}                                          int main(){ Circle circle(10);                                             cout<<"圆形的面积  =";           printArea(circle);                                                Rectangle rectangle(4,8);                                    cout<<"矩形的面积 =";                                      printArea(rectangle);                                             Triangle triangle(4,7);  cout<<"三角形的面积  ="; printArea(triangle);           return 0;}
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